Hydrochloric Acid → 4,5-Dihydro-8-methylthio-2-phenylfuro[3,4-e]benzothiazole-6-carboxylic acid

HRID 1936875Notes

Reaction equation

[CH3:1][S:2][C:3]1[O:4][C:5]([C:21]([O:23]CC)=[O:22])=[C:6]2[C:20]=1[C:10]1[N:11]=[C:12]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=3)[S:13][C:9]=1[CH2:8][CH2:7]2.C(O)C.[OH-].[Na+].Cl>O.O1CCCC1>[CH3:1][S:2][C:3]1[O:4][C:5]([C:21]([OH:23])=[O:22])=[C:6]2[C:20]=1[C:10]1[N:11]=[C:12]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=3)[S:13][C:9]=1[CH2:8][CH2:7]2

Participants

Conditions

Temperature: 50 °C

Procedure

Ethyl 4,5-dihydro-8-methylthio-2-phenylfuro[3,4-e]benzothiazole-6-carboxylate (1.32 g) was suspended in a mixed solvent of ethanol (10 ml) and tetrahydrofuran (15 ml); a 2 N aqueous solution of sodium hydroxide (5.3 ml) was added at 50° C. After the reaction mixture was stirred at 50° C. for 1.5 hours, the solution obtained was poured over water (300 ml), acidified with concentrated hydrochloric acid, and extracted with ethyl acetate-tetrahydrofuran (3:1, v/v). The organic layer was washed with water and dried (MgSO4), after which the solvent was distilled off to yield 4,5-dihydro-8-methylthio-2-phenylfuro[3,4-e]benzothiazole-6-carboxylic acid (1.14 g, 93.4%), which was then recrystallized from chloroform-methanol. Colorless prisms. Melting point 206-207° C. (decomposed).

Workup

customthe solution obtained
extractionextracted with ethyl acetate-tetrahydrofuran (3:1
washThe organic layer was washed with water
dry with materialdried (MgSO4)
distillationafter which the solvent was distilled off

Sources & evidence

ORD record: ord-cafa0fd8ddd0494ab150bbda53ef2985
Source dataset: uspto-grants-2002_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06391905B1

Reaction notes

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